The present invention relates to an unlimited sliding ball spline assembly (hereinafter, referred to as "ball spline assembly" for simplicity) adapted to receive a spline shaft therein. Such a ball spline assembly can be incorporated, as a united body, into machine tools, industrial machines and transportation apparatus. Those machines and apparatus can be used very efficiently and the fields of their use can be broadened by the adoption of a ball spline assembly contemplated herein.
More specifically, this invention relates to an improved ball spline assembly in which a ball spline bearing can be made to slide while holding both ends of a spline shaft or the torque of the spline shaft can be transmitted to the ball spline bearing, or the ball spline bearing can be made to slide while allowing the torque of the spline shaft to be transmitted to the ball spline bearing.